Re: kvm-unit-test failures

[Paolo Bonzini <pbonzini@redhat.com>]

Il 02/09/2014 21:57, Chris J Arges ha scritto:
> Seconds get from host:     1409687073
> Seconds get from kvmclock: 1409333034
> Offset:                    -354039
> offset too large!
> Check the stability of raw cycle ...
> Worst warp -354462672821748
> Total vcpus: 2
> Test  loops: 10000000
> Total warps:  1
> Total stalls: 0
> Worst warp:   -354462672821748
> Raw cycle is not stable
> Monotonic cycle test:
> Worst warp -354455286691490

Looks like one CPU is not being initialized correctly:

- The "next" correction in the trace is 18445647546048704244,
  and (next-2^64) / -354039 is about 3.1*10^9.  This is a pretty
  plausible value of the TSC frequency.  As a comparison, on my machine
  I have next=18446366988261784997 and an uptime of 29:12 hours, and
  the two match nicely with the CPU clock:

  -(18446366988261784997-2^64) / (29.2 * 3600 * 10^9) = 3.587

  $ grep -m1 model.name /proc/cpuinfo
  model name	: Intel(R) Xeon(R) CPU E5-1620 0 @ 3.60GHz

- The offset in seconds * 10^9 is pretty close to the warp in nanoseconds.

Can you: 1) try this patch 2) gather a new trace 3) include uptime and
cpuinfo in your report?  All this without clocksource=hpet of course.

Thanks,

Paolo

diff --git a/x86/kvmclock_test.c b/x86/kvmclock_test.c
index 52a43fb..f68881c 100644
--- a/x86/kvmclock_test.c
+++ b/x86/kvmclock_test.c
@@ -7,6 +7,9 @@
 #define DEFAULT_TEST_LOOPS 100000000L
 #define DEFAULT_THRESHOLD  5L
 
+long threshold = DEFAULT_THRESHOLD;
+int nerr = 0;
+
 struct test_info {
         struct spinlock lock;
         long loops;               /* test loops */
@@ -20,8 +23,9 @@ struct test_info {
 
 struct test_info ti[4];
 
-static int wallclock_test(long sec, long threshold)
+static void wallclock_test(void *p_sec)
 {
+	long sec = *(long *)p_sec;
         long ksec, offset;
         struct timespec ts;
 
@@ -36,10 +40,8 @@ static int wallclock_test(long sec, long threshold)
 
         if (offset > threshold || offset < -threshold) {
                 printf("offset too large!\n");
-                return 1;
+                nerr++;
         }
-
-        return 0;
 }
 
 static void kvm_clock_test(void *data)
@@ -116,10 +118,9 @@ static int cycle_test(int ncpus, long loops, int check, struct test_info *ti)
 int main(int ac, char **av)
 {
         int ncpus;
-        int nerr = 0, i;
+        int i;
         long loops = DEFAULT_TEST_LOOPS;
         long sec = 0;
-        long threshold = DEFAULT_THRESHOLD;
 
         if (ac > 1)
                 loops = atol(av[1]);
@@ -137,7 +138,8 @@ int main(int ac, char **av)
                 on_cpu(i, kvm_clock_init, (void *)0);
 
         if (ac > 2)
-                nerr += wallclock_test(sec, threshold);
+	        for (i = 0; i < ncpus; ++i)
+	                on_cpu(i, wallclock_test, &sec);
 
         printf("Check the stability of raw cycle ...\n");
         pvclock_set_flags(PVCLOCK_TSC_STABLE_BIT